1. The Field of the Invention
The present invention relates to a circuit and system for selecting and evaluating an optical communication channel. In particular, the invention relates to an optical integrated in-line switching device for selecting a specific communication channel for evaluation.
2. Background and Related Art
Communication system channels have largely been composed of metallic conductors such as copper or other low resistance metals. Systems using such conductors have generally been relatively easy to monitor and evaluate without great disruption or intrusion into the communication channel since current flows throughout the entire conductor and portions of the conductor can be externally “tapped” with another conductor attached to the test equipment that bleeds-off a negligible amount of test current.
Additionally, conductive fibers that transmit light have also been used as communication channel medium and have proven to be advantageous for the transmission of large amounts of information, both in digital and analog form. Fiber conductors, unlike metallic conductors, propagate the information signal in a very longitudinally directional path. Furthermore, the information signal propagates down a very narrow internal portion of the conductor making the non-intrusive external “tapping” of the fiber impractical.
Therefore, in order to monitor a fiber channel, a splitter also known as a coupler, must be placed “in-line” with the fiber channel to reflect a portion of the light from the main conductive fiber channel to another conductive fiber channel that can be coupled to a network analyzer or other test equipment. In FIG. 1, a system 100 for monitoring a plurality of fiber channels 102–108 is depicted with a corresponding plurality of dedicated couplers 110–116 connecting with a corresponding plurality of dedicated test equipment 118–124. While such an arrangement makes in-line testing possible, the installation of such couplers into the individual channels has been complex and tedious.
Additionally, even when the couplers are inserted into the various individual fiber channels, the logistics and expense of connecting dedicated test equipment to each channel soon becomes prohibitively expensive. Also, even if a single piece of test equipment is reused on multiple channels, the logistics of disconnecting and reconnecting to each of the various couplers becomes expensive, tedious, and, especially when remote monitoring is desired, impractical or impossible to timely access and physically re-couple with each of the channels.
There is a need to provide a non-intrusive solution that efficiently uses network analysis resources while allowing the channel to remain intact without interrupting the flow of traffic on the channel. Furthermore, a need exists for providing convenient selection of channels for monitoring without impacting the flow of communications traffic on the channel under analysis. There further exists a need to efficiently utilize test equipment without requiring deployment of a full suite of test equipment dedicated to each communication channel.